Solvothermal Alcoholysis Research Articles

Molybdenum oxide-iron, cobalt, copper alloy hybrid as efficient bifunctional catalyst for alkali water electrolysis

Efficient and durable non-precious catalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is pivotal for practical water electrolysis toward clean hydrogen fuel. Herein, a molybdenum oxide-FeCoCu alloy hybrid (MoOx-FeCoCu) catalyst was designed by polyoxometallate (POM) molecular cluster mediated solvothermal alcoholysis and ammonolysis of metal salts followed by pyrolytic reduction treatment. The HER efficiency is substantially enhanced by the ternary alloy component, which is more close to the benchmark Pt/C catalyst, and the HER catalytic stability is also superior to Pt/C catalyst. Moreover, the MoOx-FeCoCu demonstrates high catalytic efficiency and rather good durability for OER. Benefitted by the bifunctional catalytic behaviors for HER and OER, the symmetric water electrolyzer based on the MoOx-FeCoCu electrode requires a low driving voltage of 1.69 V to deliver a response current density of 10 mA cm−2, which is comparable to that based on the benchmark Pt/C HER cathode and RuO2 OER anode. The current work offers a feasible way to design efficient bifunctional catalyst for water electrolysis via POM mediated co-assembly and calcination treatment.

Solvothermal Alcoholysis Method for Recycling High-Consistency Silicone Rubber Waste

In this work, we investigated the potential use of high-consistency silicone rubber (SR), which is a synthetic solid material used in numerous industrial applications, to produce a range of liquid alkoxysiloxane derivatives R(OSiMe₂)ₓOR, with x = 1 (P₁), 2 (P₂), 3 (P₃), and 4 (P₄). We describe a simple and convenient solvothermal alcoholysis method for the chemical recycling of post-consumer SR in the presence of fatty alcohols under catalyst-free or catalytic conditions. This process proceeds easily both without and with a catalyst. Alkali-metal aryloxides supported by a methylsalicylato ligand (MesalO) gave the highest conversions of SR to products P₁–P₄. Magnesium and zinc aryloxides enabled efficient conversions of products P₂–P₄ to P₁. Binary metal catalysts of general formula [M₂M′₂(MesalO)₆] (M = Mg or Zn; M′ = Li, Na, or K), which had a combination of the catalytic properties shown by alkali-metal aryloxides and magnesium/zinc aryloxides, were produced and used to synthesize P₁–P₄. The results show that magnesium–sodium/potassium aryloxides had the best catalytic activities. Their use led to the formation of two dominant products, namely, P₁ and P₂, with conversion yields of 79 and 17%, respectively. Particular emphasis is placed on the operating conditions and high activity of the catalyst used. Key factors that affect the catalytic activity and reaction mechanism are also highlighted.

Study on Effect of the Solvothermal Temperature on Synthesis of 3D Hierarchical TiO2 Nanoflower and Its Application as Photocatalyst in Degradation of Organic Pollutants in Wastewater

3D TiO2 hierarchical nanoflower was synthesized by template-free solvothermal alcoholysis of TiCl3 with the variation of reaction temperatures (130–200 °C). XRD, SEM, BET surface analysis, UV–VIS DR spectroscopy, FTIR analysis were performed to characterize the prepared TiO2 samples. Photocatalytic degradation of model organic pollutant such as methylene blue (MB) dye was investigated using all prepared samples under UV light illumination. Results show that reaction temperature directly affects the anatase phase content of TiO2 samples, crystal structures, crystalline size, particle size, surface area, pore structure, UV absorption capacity, and band gap of the synthesized samples. The sample prepared at reaction temperature 150 °C seems to be most efficient photocatalyst for degradation of MB with rate constant 0.0287 min−1 [~ 20.5 times higher than the sample prepared at 130 °C (0.0014 min−1) and 6.83 times higher than the sample prepared at 200 °C, (0.0042 min−1)]. Optimization of reaction temperature at 150 °C was performed by testing different properties of the synthesized TiO2 nanoflower such as its surface area, organized morphology, bimodal pore-size distribution, and porosity which were synthesized at different solvothermal temperatures (130–200 °C).

Unveiling the relationships between (010) facets-orientation growth and photocatalytic activity in W18O49 nanowires

Crystal facets-orientation growth plays a crucial role in determining photocatalytic performance. Herein, a series of (010) facets-oriented W18O49 nanowires were controllably synthesized by a facile solvothermal alcoholysis method using octadecylamine as the crystal growth capping agent in order to regulate the specific growth behavior and unveil its correlation with photocatalytic performance. The properties of the prepared W18O49 nanowires, such as surface oxygen vacancies, light absorption and the band gap size, as well as the surface charge carriers separation rate, could be well-modulated via tailoring the preferred orientation growth. The W18O49 nanowire with the strongest (010)-faceted orientation demonstrated the best photocatalytic degradation of Methyl Orange under ultraviolet light irradiation (up to 100% within 15 min) and visible light irradiation (up to 91% within 95 min). These interesting findings not only help us to gain an in-depth understanding of the relationship between the preferred orientation growth and the photocatalytic performance but also have the potential to open up an innovative route/protocols for the preparation of crystal facets-oriented metal oxides for highly efficient photocatalysis.

Solvothermal alcoholysis synthesis of hierarchically porous TiO2-carbon tubular composites as high-performance anodes for lithium-ion batteries

Hierarchically porous one-dimensional (1D) TiO2-carbon tubular composites (TiO2C-Ts) with interconnected nanoflakes on the porous tube walls, have been successfully created using a simple solvothermal alcoholysis followed by a subsequent calcination process. The as-prepared TiO2C-Ts demonstrate high electrical conductivity due to the 1D tubular frameworks and the interconnected porous tube walls, offering fast ion/electron transport paths and large space for storing the electrolyte, while buffering the volume change during the Li+ insertion/extraction process. When evaluated as an anode in a lithium-ion battery, the optimized TiO2C-Ts600 electrode displays a remarkable reversible capacity of 534 mA h g−1 after 100 cycles at 180 mA g−1 and an impressive capacity of 284.9 mA h g−1 (∼80% capacity retention) after 3000 cycles at 3.5 A g−1. Further, the performance of the TiO2C-Ts600 electrode is also investigated in a full cell using LiFePO4 as the cathode, demonstrating highly reversible discharge capacity (353.8 mA h g−1 after 100 cycles at 100 mA g−1, corresponding to capacity retention of ∼73%) and superior rate capability (254.4 mA h g−1 at 1.0 A g−1), suggesting its great potential application in high-performance energy storage devices.

Highly improved acetone oxidation activity over mesoporous hollow nanospherical MnxCo3−xO4 solid solutions

Mesoporous hollow nanospherical MnxCo3−xO4 solid solutions synthesized by a facile solvothermal alcoholysis have been developed to catalyze acetone oxidation for the first time.

Boosting total oxidation of acetone over spinel MCo2O4 (M = Co, Ni, Cu) hollow mesoporous spheres by cation-substituting effect

Boosting total oxidation of volatile organic compounds (VOCs) over spinel Co3O4 by cation-substituting effect is an effective solution, but the underlying mechanism has not yet been clearly elucidated. Herein, a series of spinel MCo2O4 (M = Co, Ni, Cu) hollow mesoporous spheres (HMS) have been synthesized by solvothermal alcoholysis with goals to elaborate the cation-substituting effect on spinel Co3O4 for total oxidation of VOCs. The physicochemical properties of spinel MCo2O4 (M = Co, Ni, Cu) HMS have been well characterized and correlated with their catalytic activities. Results reveal that CuCo2O4 HMS exhibited superior catalytic activity than those of NiCo2O4 and CoCo2O4 HMS for total oxidation of acetone and their catalytic activities followed the sequence of CuCo2O4 > NiCo2O4 > CoCo2O4. This phenomenon can be attributed to the cation-substituting effect, which resulted in the synthesized catalysts with different amounts of surface Co3+ cations, active oxygen species, defective sites and reducible capabilities. Meanwhile, kinetics studies offer direct evidence to support that the cation-substituting effect played the decisive role in determining the catalytic activity, and the underlying mechanism has been proposed by correlating the structure-activity relationship. Moreover, CuCo2O4 HMS also showed excellent long-term stability and good water tolerance due to its highly stable crystal phase and robust morphological structure, demonstrating its potential applications in the field of VOCs elimination.

Facile synthesis of TiO2 microspheres via solvothermal alcoholysis method for high performance dye-sensitized solar cells

TiO2 microspheres (MS-TiO2) are synthesized by a facile one-step nonaqueous solvothermal alcoholysis method. Without any post-processing, the as-prepared MS-TiO2 constituted by high crystallinity anatase nanoparticles (∼18 nm) exhibits large specific surface area (114 m2 g−1), high porosity (71%), and wide pore size distribution (centered at ∼12.4 nm, average pore diameter is ∼20.9 nm). Moreover, the MS-TiO2 shows superior light scattering ability. When employed as photoanode in dye-sensitized solar cells, the MS-TiO2 films display excellent dye loading capacity and good light-harvesting capabilities in the range of 400–700 nm. Consequently, an ultrahigh short circuit current density up to 20.41 mA cm−2 and a high power conversion efficiency of 10.35% are achieved by the MS-TiO2 based solar cells.

Solvothermal Alcoholysis Routes for Recycling Polylactide Waste as Lactic Acid Esters

In this work, we investigated the possible use of polylactide (PLA), a biodegradable polymer obtained from renewable biofeedstock, to produce a range of industrially useful lactic acid esters. We describe a simple and convenient solvothermal alcoholysis method for large-scale recycling of PLA resins or residues from disposable packaging in the presence of the appropriate alcohol under catalyst-free or catalytic conditions. This process proceeds easily both without and with a catalyst. The results show that the best catalytic activities involve magnesium and calcium alkoxides synthesized in situ from organometallic or metallic precursors and an alcohol. We determined the crystal structure of the chiral mononuclear postcatalyst [Ca(LAc)2(EL)2] (1; LAc = lactic acid anion, EL = ethyl lactate), obtained directly from the reactor. Particular emphasis is placed on the operating conditions and high activity of the catalyst used. Key factors that affect the catalytic activity and reaction mechanism are also highl...

A Post-Functionalizable Iso-Polyoxotitanate Cage Cluster.

During solvothermal alcoholysis of a mixture of TiI4 and Ti(O(i)Pr)4, a {I@Ti22} cage cluster encapsulating an OH and iodide guests is crystallized. The {I@Ti22} host-guest cluster surface is postfunctionalizable with catecholate and carboxylate ligands. The synthetic details, structural characterization, spectroscopic properties of the obtained cages clusters are provided. The present study provides candidates for modeling ligand exchange and electron-hole transfer at the titanate nanoparticle surface, and meanwhile offers new opportunities for understanding the TiO2 nanocrystalline formation in solvothermal processes.

TiO2 mesocrystal with exposed (001) facets and CdS quantum dots as an active visible photocatalyst for selective oxidation reactions

CdS quantum dots decorated TiO2 mesocrystals with exposed (001) facets were synthesized by solvothermal alcoholysis and subsequent ion-exchange. The as-prepared photocatalyst exhibited high activity and selectivity in selective oxidations of various alcohols to their corresponding aldehydes under visible light irradiation. The high photocatalytic efficiency could be ascribed to the CdS quantum dots with enhanced photosensitizing effect and CdS-TiO2 heterojunction, the mesoporous structure with high surface area, and the exposed (001) facets with high surface energy and large number of oxygen vacancies, which promoted the light-harvesting, photocatalyst activation by visible lights, photoelectron-hole separation, reactant molecule adsorption and activation. Moreover, it also showed strong durability owing to the excellent stability against structural collapse and either CdS leaching or CdS corrosion.

Highly porous TiO2 hollow microspheres constructed by radially oriented nanorods chains for high capacity, high rate and long cycle capability lithium battery

Hierarchical nanorods chains-constructed TiO2 hollow microspheres (HNC-TiO2-HMSs) have been designed and prepared through a facile one-pot fluorine-free solvothermal alcoholysis route using TiCl4 and isopropanol reaction system. Owing to the assembly of radially oriented nanorods chains leading to the formation of the shell of the hollow spheres, a large series of straight channels along nanorods chains are formed. Such highly porous hollow microspheres with hollow cavity, straight nanorods chains and straight nanochannels are highly desirable for Li ions batteries because such structure can easily store the electrolyte, facilitate the charge diffusion and Li+ insertion and buffer the volume change during the Li+ insertion/extraction process. One of the key innovation of the present work is the fine tuning of water amount released from the esterification of alcohol to induce in a well controlled hydrolysis of TiCl4 and engineer precisely HNC-TiO2-HMSs formation. Most importantly, the released Cl− ions direct the nanorods growing along (001) crystal plane and self-assembling along the radial direction accompanying with nanorods size controlling to form HNC-TiO2-HMSs. The obtained TiO2 anode material with such special structure demonstrates excellent Li+ storage capacity with outstanding cycle performance and superior rate capability at different rates over 700 cycles: a reversible capacity of 216mAhg−1 is obtained after 100 cycles at 1C and a reversible capacity of 112mAhg−1 is retained after 100 cycles at 10C. The SEM, TEM, HRTEM and in-situ XRD techniques have been utilized to shed light on the Li+ insertion process and the phase transformation. Most importantly, a self-improving phenomenon of cycle performance and storage capacity was observed owing to the formation of numerous ~5nm Li2Ti2O4 nanocrystals formed on the surface of the nanorods chains. The results reveal that the high performance of the as-prepared HNC-TiO2-HMSs in terms of storage capacity, cycle performance and rate capability can be attributed to the synergy of the special structure and the self-improving phenomenon. Our simple reaction system may provide a concrete example on the construction of novel hollow spherical porous anode materials for high performance lithium batteries.

Hierarchical CoS2@C hollow microspheres constructed by nanosheets with superior lithium storage

An effective approach of alcoholysis is employed to prepare hollow CoS2@C hybrid nanosheets aggregates as anode materials for Li-ion batteries. Amorphous carbon can be loaded on the CoS2 nanoparticles uniformly in the solvothermal alcoholysis process, and the subsequent calcination results of the formation of hollow structures. The capacity of the sample can remain stable as high as 720 mAhg−1 after 200 cycles, and it also exhibits good rate capacity. The nano-scaled characteristics of CoS2 nanosheets embedded in the aggregates ensure the electrode having a high capacity and the fast Li-ion diffusion in the electrode. The in-situ introduction of carbon renders the electrode having a good electronic conductivity and can effectively prevent the formation of polysulfide anions. The unique hollow structures can shorten the length of Li-ion diffusion, which is benefit for the rate performance. The hollow structure also offers a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. Therefore, the prepared hierarchical hollow CoS2@C materials constructed by nanosheets exhibit outstanding electrochemical performance.

Preparation of TiOxNy/TiN composites for photocatalytic hydrogen evolution under visible light.

TiOxNy/TiN heterojunction composites with tunable chamber structures were prepared through reduction and nitridation of organotitania obtained via solvothermal alcoholysis at 900 °C for 4 h in partially cracked NH3. Owing to the low synthesis temperature, TiOxNy/TiN duplicates the original structure of organotitania. It also demonstrates an outstanding activity toward hydrogen production as high as 34.9 μmol h(-1) g(-1), which is about 1.5 times higher than the highest value reported in the literature for the TiN material. The enhanced photoactivity can be ascribed to the heterojunction structure, which is beneficial for separating the photogenerated carriers in space.

Dye-sensitized solar cells with enhanced efficiency using hierarchical TiO2spheres as a scattering layer

TiO2 microspheres with solid, core–shell and hollow chambers were synthesized by facile solvothermal alcoholysis. The TiO2 microspheres were encapsulated between TiO2 films comprising of tiny nanoparticles and used as a scattering layer in dye-sensitized solar cells (DSSCs). The resulting DSSCs showed increased cell efficiencies compared to those of pure TiO2 films without any scattering layers. DSSCs with hollow microspheres as scattering layer exhibited the highest photocurrent due to the enhanced light harvesting, which could be attributed to both the multiple reflections of light in the chamber and total internal reflections. Moreover, it also facilitated electron transfer and increased the lifetime of photocharges.

Robust non-carbon titanium nitride nanotubes supported Pt catalyst with enhanced catalytic activity and durability for methanol oxidation reaction

By the combination of solvothermal alcoholysis and post-nitriding method, titanium nitride nanotubes (TiN NTs), with high surface area, hollow and interior porous structure are prepared successfully and used at a support for Pt nanoparticles. The TiN NTs supported Pt (Pt/TiN NTs) catalyst displays enhanced activity and durability towards methanol oxidation reaction (MOR) compared with the commercial Pt/C (E-TEK) catalyst. X ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements are performed to investigate the physicochemical properties of the synthesized catalyst. SEM and TEM images reveal that the wall of the TiN NTs is porous and Pt nanoparticles supported on the dendritic TiN nanocrystals exhibit small size and good dispersion. Effects of inherent corrosion-resistant, tubular and porous nanostructures and electron transfer due to the strong metal–support interactions of TiN NTs contribute to the enhanced catalytic activity and stability of Pt/TiN NTs towards the MOR.

ChemInform Abstract: Hierarchical Synthesis of Mo—Sn Oxide Cage‐Bell Hybrid Structures with Superior Lithium Storage.

AbstractMoO3‐SnO2@C oxide cage‐bell hybrid nanoparticle aggregates are prepared by a facile Ostwald ripening via solvothermal alcoholysis of SnCl2 and (NH4)6Mo7O24, and sucrose in a mixture of EtOH and glycerol (180 °C, 6‐48 h) followed by drying (60 °C, 12 h) and thermal oxidation (400 °C, 2 h).

Hierarchical synthesis of Mo–Sn oxide cage-bell hybrid structures with superior lithium storage

A facile generic solvothermal alcoholysis strategy is employed to prepare Mo-Sn oxide cage-bell hybrid nanoparticle aggregates. The intrinsic hollow core-shell nature as well as the multi-element characteristics of active components of the unique nanostructures contribute greatly to the enhanced performance as anode materials for lithium ion batteries.

Template‐Free Fabrication of Hollow NiO–Carbon Hybrid Nanoparticle Aggregates with Improved Lithium Storage

Hollow NiO–carbon hybrid nanoparticle aggregates are fabricated through an environmental template‐free solvothermal alcoholysis route. Controlled hollow structure is achieved by adjusting the ratio of ethylene glycol to water and reaction time of solvothermal alcoholysis. Amorphous carbon can be loaded on the NiO nanoparticles uniformly in the solvothermal alcoholysis process, and the subsequent calcination results in the formation of hollow NiO–C hybrid nanoparticle aggregates. As anode materials for lithium‐ion batteries, it exhibits a stable reversible capacity of 622 mAh g−1, and capacity retention keeps over 90.7% after 100 cycles at constant current density of 200 mA g−1. The NiO–C electrode also exhibits good rate capabilities. The unique hollow structures can shorten the length of Li‐ion diffusion and offer a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. The hybrid carbon in the particles renders the electrode having a good electronic conductivity. Here, the hollow NiO‐C hybrid electrode exhibits excellent electrochemical performance.

Mesoporous TiN Microspheres with Hierarchical Chambers and Enhanced Visible Light‐Driven Hydrogen Evolution

Mesoporous titanium nitride (TiN) microspheres with tunable chamber structures were synthesized through NH3 nitridation of organotitania obtained via solvothermal alcoholysis. Owing to high content of organic species in organotitania, which stabilized the original structure and also promoted the nitridation at low temperature, TiN duplicated the solid, yolk-shell, and hollow chambers of organotitania in NH3 nitridation and also formed the mesoporous structure after removing organic species. During visible light-induced photocatalytic water splitting, the yolk-shell TiN demonstrated a higher H2 evolution efficiency than the solid, hollow, and crushed TiN; the yolk-shell TiN obtained through N2 nitridation; and other semiconductor photocatalysts reported so far without the aid of noble metals. This could be attributed mainly to the narrow energy band gap for absorbing visible light, high surface area, and excellent electrical conductivity, which facilitated light harvesting, reactant adsorption, and photoelectron-hole separation to suppress their recombination. Moreover, it could be easily recycled and thus used repetitively.